var W = screen.width;//取得屏幕分辨率宽度
var H = screen.height;//取得屏幕分辨率高度
var objpop ='login';
function M(id){
    return document.getElementById(id);//用M()方法代替document.getElementById(id)
}
function MC(t){
   return document.createElement(t);//用MC()方法代替document.createElement(t)
};
//判断浏览器是否为IE
function isIE(){
      return (document.all && window.ActiveXObject && !window.opera) ? true : false;
}
//取得页面的高宽
function getBodySize(){
   var bodySize = [];
   with(document.documentElement) {
    bodySize[0] = (scrollWidth>clientWidth)?scrollWidth:clientWidth;//如果滚动条的宽度大于页面的宽度，取得滚动条的宽度，否则取页面宽度
    bodySize[1] = (scrollHeight>clientHeight)?scrollHeight:clientHeight;//如果滚动条的高度大于页面的高度，取得滚动条的高度，否则取高度
   }
   return bodySize;
}
//创建遮盖层
function popCoverDiv(){
   if (M("cover_div")) {
   //如果存在遮盖层，则让其显示
    M("cover_div").style.display = 'block';
   } else {
   //否则创建遮盖层
    var coverDiv = MC('div');
    document.body.appendChild(coverDiv);
    coverDiv.id = 'cover_div';
    with(coverDiv.style) {
     position = 'absolute';
     background = '#CCCCCC';
     left = '0px';
     top = '0px';
     var bodySize = getBodySize();
     width = bodySize[0] + 'px'
     height = bodySize[1] + 'px';
     zIndex = 0;
     if (isIE()) {
      filter = "Alpha(Opacity=60)";//IE逆境
     } else {
      opacity = 0.6;
     }
    }
   }
}




//让登陆层显示为块
    function showLogin()
    {
  var login=M(objpop);
     login.style.display = "block";
}

//设置DIV层的样式
function change(){
   var login = M(objpop);
      login.style.position = "absolute";
      login.style.border = "1px solid #CCCCCC";
      login.style.background ="#F6F6F6";
      var i=0;
   var bodySize = getBodySize();
      login.style.left = (bodySize[0]-i*i*4)/2+"px";
      login.style.top = (bodySize[1]/2-100-i*i)+"px";
      login.style.width =      i*i*4 + "px";
      login.style.height = i*i*1.5 + "px";
    
      popChange(i);
}
//让DIV层大小循环增大
function popChange(i){
      var login = M(objpop);
   var bodySize = getBodySize();
      login.style.left = (bodySize[0]-i*i*4)/2+"px";
      login.style.top = (bodySize[1]/2-100-i*i)+"px";
      login.style.width =      i*i*4 + "px";
      login.style.height = i*i*1.5+ "px";
      if(i<=10){
           i++;
           setTimeout("popChange("+i+")",10);//设置超时10毫秒
      }
}
//打开DIV层
function openDiv(obj)
{
objpop = obj;
change();
showLogin();
popCoverDiv()
void(0);//不进行任何操作,如：<a href="#">aaa</a>
}
//关闭DIV层
function close(){
  M(objpop).style.display = 'none';
  M("cover_div").style.display = 'none';
void(0);
}